I have a server hosted using thermos and it is getting very good with no signs of conflict between plugins and mods, but the problem is how it is in the title, when I give / spawn, or teleport to a warp in another world, the delay to the server answering the client lasts a considerable time!

Host: 8GB Ram

even for my players near the host it looks like this!
How do I solve this?

Edit: It seems that when I start walking over the overworld and loading new chunks, the server starts to stop responding